INTRODUCTION The variability of the qualitative and quantitative response to multiple ovulation treatment remains very large (Hahn, 1992). The costs and work required by the superovulation technique are very high and the prediction of the genetic responsiveness of donor cows to actual treatments would be a valuable tool for breeders. Embryos collection is now routinely applied in Belgian Blue breed for breeding and commercial purposes. Therefore, the aim of this study is to evaluate the effects of some environmental factors and to estimate repeatability and genetic parameters for number of oocytes and embryos and for number of transferable embryos in responder cows of the Belgian Blue breed with the intent to proceed with genetic evaluation of breeding animals.